All said, Warriors cost
half two thirds of what Scallops do. Given that Valkyries are dirt cheap, Scallop cost used to be the limiting factor on rush speed. Warriors are the limiting factor in Warrior drop, but one that is twice less limiting.
The Scallop drop rush was not very easy to stop/scout in 2v2; if Warrior drop is of comparable efficiency and is twice faster, it is likely harder to prevent. It
might also be enough to fall into the rush margin at which it's blind rps.
I'm not sure if
two three games are sufficient to tell, though. Rushes do work sometimes. It wouldn't be hard to bring forth two doubled scorcher rush games and use them to claim that scorcher OP.
Now, for some theorycraft:
1: Consider when blackdawns/brawlers were faster and cheaper to make, or the 50 second gnat lockdown rush when gnats had perfect accuracy. Basically, if the rush strategy is 50 seconds to impact, it becomes blind RPS in most cases.
2: With 20 buildpower, 400 metal available at the beginning and +4 income, a single player can push out about ~480 metal worth of production before stalling in ~24 seconds.
3: It follows that anything that costs 480 metal, can cross the map in 26 seconds, and can deliver a victory is a blind rps rush.
Scallops are reasonably close to the edge of this: two players get 880 rush resource, which they spend on two scallops (280 each) and two valkyries (80 each), for 720 total, rather in the inner size of the threshold but still not far from it.
Three warriors with three valkyries for 840 are also below this threshold. Maybe they were not rushed previously because their dps and health - that is their win chance - was not high enough. Or maybe noone just considered doing it. Two flying warriors can be produced for a mere 560 metal, which is
deep into rush threshold territory.
Valkyrie could just cost a bit more to push the triple warrior drop over the threshold, but if two warriors are sufficient to grant a solid kill chance, that won't be enough.
(Worth noting: three slashers and rocket commander, or 3-4 scorchers also can fall into the blind rush category if map is of the proper size. But noone complains.)